This application relates to medical x-ray positioners and in particular to a positioner using independently articulated arms to support the x-ray source and x-ray detector particularly suited for tracking a contrast bolus moving within a patient.
Conventional x-ray positioners provide mechanical supports to hold an x-ray source and x-ray detector in opposition about a patient for a limited number of specific procedures. For procedures in which the patient is standing, the x-ray source may be attached to a pillar allowing adjustment in its height as directed toward an x-ray detector attached to an opposing wall or a second similar pillar. For procedures in which the patient is supine, the x-ray source and detector may be attached to opposite sides of a patient table. Alternatively the x-ray source and the detector may be attached to opposite ends of a C-arm which is supported by a sliding collar allowing the angle of the x-rays through the patient to be varied.
Multi-axis robotic arms, positioned above and below the patient table, have been proposed to provide support for the x-ray source and x-ray detector such as may reduce interference between the support structure and other equipment and personnel. See, for example, U.S. Pat. No. 6,200,024 to Negrelli citing U.S. Pat. No. 4,894,855 to Kresse.
Such systems require complex multi-axis movement for simple adjustments of the x-ray tube and detector in angulation or translation, and appear to have limited utility for certain common x-ray procedures such as those requiring the patient to stand. Further such systems make it difficult or impossible to swap the location of the x-ray source from beneath the patient to above the patient, when the patient is supine, and an improved image might thereby be obtained. The limited axes of freedom provided by conventional positioners limit their ability to automatically track a bolus travelling through a patient""s body.
The present invention provides an x-ray positioner having increased axes of freedom compared to conventional systems to enable the positioner to automatically track the movement of a bolus through a patient. Generally the invention provides a bolus tracking x-ray positioner having an x-ray source producing an x-ray beam directed along a source axis, and an x-ray detector detecting x-rays received along a detector axis. A first and second articulated arm holds respectively the x-ray source and the x-ray detector in opposition about a patient volume for movement along a bolus path. An axis controller operates according to a stored program to: (i) recieve image signals from the x-ray detector, (ii) process the image signals to identify movement of a bolus of contrast medium within a patient, and (iii) send movement signals to the first and second articulated arms to move the x-ray source and x-ray detector to follow the bolus with movement of the bolus through the patient.